Multivariate Hot-Drought Risk Assessment: The 2014 California Drought

Wednesday, April 22, 2015
Omid Mazdiyasni, Amir AghaKouchak, Linyin Cheng and Alireza Farahmand, University of California Irvine, Irvine, CA, United States
Droughts have great impacts on society, the economy, and the environment, however when a drought is coupled with extreme temperatures, the risk of climate induced catastrophe substantially increases. The 2014 California drought is an archetype of an event characterized by low precipitation and extremely high temperatures. From the raging wildfires, to record low storage levels and snowpack conditions, the impacts of this event can be felt throughout California. Wintertime water shortages worry decision-makers the most because it is the season to build up water supplies for the rest of the year. Here we show that the traditional univariate risk assessment methods based on precipitation conditions may substantially underestimate the risk of extreme events such as the 2014 California drought because it ignores the effects of high temperatures. We argue that a multivariate viewpoint is necessary for assessing risk of extreme events. This study discusses a methodology for assessing the risk of concurrent extremes such as droughts and extreme temperatures.